1. Field of the Invention
The present invention relates to a cabinet configured to contain a desired device and to have, on a side portion thereof, an additional device which operates in association with or in parallel with the desired device, and it relates to the additional device.
2. Description of the Related Art
In recent years, various operators employ cabinets in compliance with the EIA standard or the JIS standard to accommodate many devices such as routers and servers of a data communication network which are given maintenance and expansion when necessary, the cabinet containing these devices together in the same site or office premise (may be a single rack).
FIG. 10(a) and FIG. 10(b) show a structural example (1) of a conventional cabinet.
FIG. 11 shows a structural example (2) of the conventional cabinet.
As shown in FIG. 10(a), FIG. 10(b), and FIG. 11, the conventional cabinet is composed of the following elements:    (1) A cylinder 52 made of metal (aluminum or the like) having: two apertures with one edge folded with a margin of a prescribed width (assumed here to be small to such an extent as not to close the aperture) at a right angle in a direction of the axis of the cylinder; attached thereto a printed board 51 with components constituting a desired device (a router or the like) mounted in a hollow portion thereof; and a cross section thereof in a rectangular shape;    (2) A front cover 53: connected to an electronic circuit (including later-described receptacles 51R-1, 51R-2) on the printed board 51; having attached thereto electronic components used for connection of the electronic circuit to a man-machine interface and to an exterior; fitted (or fastened) to the aperture of the aforesaid cylinder 52 with no folded edge; having in advance a slit or the like corresponding to a ventilation path to the exterior in advance and preventable of radiation of electro magnetic interference generated in the electronic circuit to the exterior;    (3) A decorative frame 56 having a cross section in a substantially U shape and covering the aforesaid cylinder 52 and both of cabinets 55-1, 55-2 (assumed here that a width w thereof is half (=W/2) a width W (<19 inch) of the aforesaid aperture, and a thickness t thereof is equal to a thickness T of this aperture) containing later-described two power supply units 54-1, 54-2 (the power supply unit 54-2 is omitted in FIG. 10(a) and FIG. 10(b) in order to clearly show the inside of the cylinder 52) adjacent to the aperture, the cabinets 55-1, 55-2 being made of metal in a rectangular parallelepiped shape to contain part of the power supply units 54-1, 54-2 respectively.
The aforesaid cabinet 55-1 is formed in the following manner:    (1) A bending margin that is equal in size and shape to the aforesaid bending margin is reserved in an aperture at the one aperture of the cylinder 52, and the bending margin is bent at a right angle in a direction so as to narrow this aperture.    (2) A bottom of the cabinet 55-1 is formed as a detachable metal plate 55B-1.    (3) Two air vents 57-11, 57-12 and two decorative screws 58-11, 58-12 rotatable from an exterior are attached to predetermined positions of the plate 55B-1, and fans 59-11, 59-12 are mounted inside the air vents 57-11, 57-12.    (4) Screw holes formed in the bending margins of the apertures of the cabinet 55-1 and the cylinder 52, for a predetermined number of screws to screw-fix the cabinet 55-1 and the cylinder 52 to each other.
Further, the power supply unit 54-1 is constituted of the following elements:    (1) a printed board 61 fixed to the aforesaid plate 55B-1 at one end and having at the other end thereof a plug 60P-1 fitted to the receptacle 51R-1; and    (2) a power supply circuit 62-1 formed on the printed board 61-1 to supply power to the circuit disposed on the printed board 51 via the aforesaid plug 60P-1 and receptacle 51R-1 and to drive the fans 59-11, 59-12.
Since the structures of the power supply units 54-2 and the cabinet 55-2 are the same as those of the power supply unit 54-1 and the cabinet 55-1 respectively, explanation and illustration thereof will be omitted here, and the same reference numerals and symbols with a suffix number ‘2’ instead of ‘1’ will be used to designate corresponding portions.
A device including the cabinet as configured above is assembled in the following procedure.    (1) The printed board 51 whose assembly has been finished is mounted in the hollow portion of the cylinder 52.    (2) The front cover 53 is attached to the other aperture of the cylinder 52.    (3) The decorative screws 58-11, 58-12, 58-21, 58-22 are screwed off from the power supply units 54-1, 54-2 whose assembly has been finished, and the plates 55B-1, 55B-2 are detached from the bottoms of the cabinets 55-1, 55-2. It is assumed that even during this process, power supply routes to the fans 59-11, 59-12 are kept via lead wires connected to the power supply circuits 62-1, 62-2 respectively.    (4) Screws used for screw-fixing the apertures of the cabinets 55-1, 55-2 to the one aperture of the cylinder 52 from the bottom (holes formed by the aforesaid detachment of the plates 55B-1, 55B-2) side of the cabinets 55-1, 55-2.    (5) The bottoms of the cabinets 55-1, 55-2 are closed with the plates 55B-1, 55B-2 through performing the above procedure in reverse (3).    (6) The decorative frame 56 is placed to cover an external wall except bottom faces of the cabinets 55-1, 55-2 and the cylinder 52.
A prior art to enhance or maintain high stiffness of a cabinet similarly to the present invention is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2001-148578.
In the above-described conventional example, in order to prevent radiation of electronic magnetic interference generated in the electronic circuit disposed on the printed board 51 to the exterior of the cabinet, it is necessary to electrically tightly connect the cylinder 52 to the cabinets 55-1, 55-2 by the aforesaid screw-fixing or to similarly maintain stable and close electrical connection between the cylinder 52 and the cabinets 55-1, 55-2 via conductive springs 71 or the like as shown by (1) in FIG. 12.
Further, the springs 71 give a strong pressure to the apertures of the cylinder 52 and the cabinets 55-1, 55-2. Generally, however, the cylinder 52 and the cabinets 55-1, 55-2 are preferably thin and made of light-weight metal so that the cylinder 52 is required to have a reinforcing member 72 at least near the aperture in order to prevent it from deforming against the pressure as shown by (2) in FIG. 12.
However, the bending margin of the aperture of the cylinder 52 reduces the volume of an available space in the hollow portion of the cylinder 52 in which desired components including the aforesaid printed board 51 are disposed. In addition, even without such a bending margin, the available space is narrowed by the aforesaid reinforcing member 72 and the springs 71, which possibly prevents desired high density assembly and downsizing of the cylinder.
Moreover, in the conventional example, the cylinder 52 and the cabinets 55-1, 55-2 are electrically closely coupled in order to suppress radiation of the electro magnetic interference in a high-frequency band ranging from several mega hertz to several gigahertz generated in the electronic circuit on the printed board 51 and of the electro magnetic interference in a bandwidth of several hundred kilohertz or less generated in the power supply circuits 62-1, 62-2 during the process of voltage conversion by switching.
Therefore, for example, with the power supply unit 54-2 detached for replacement or not mounted, the power supply and forced air cooling relies on the power supply unit 54-1, so that an expensive shield has to be provided in order to prevent the radiation of the electro magnetic interference in a high-frequency band.
Moreover, in the conventional example, the heat release efficiency of the electronic circuit lowers if either of the power supply units 54-1, 54-2 is not mounted or either of the fans incorporated therein is in fault. Therefore, it is required to set the performance or the rotation speed of the fans 59-11, 59-12, 59-21, 59-22 with a sufficient margin so as to maintain the operational temperature of the electronic circuit while the power is continuously supplied to the electronic circuit.
Generally, when power supply units to be plugged into the cabinets of individual devices do not incorporate fans, the larger the number of devices contained in the rack and the thinner the thickness of the cabinets in which the bodies of the devices are mounted, with higher assembly density many power supply units and fans are mounted. Besides, it is difficult to make air exhaustion or suction in the same direction by the fans.
In such a case, it is likely that the size of the cabinets of the devices contained in the same rack increases since the rack needs to have complex ventilation paths for the purpose of compensating or adapting to the exhaustion and suction in various directions.